JP2007040699A - Roller hearth type continuous furnace - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a roller hearth type continuous furnace capable of suppressing the occurrence of a strain to a plate-form substance to be heated even with the plate-form substance to be heated placed directly on a hearth roller without using a setter. <P>SOLUTION: A pitch distance (d) of the hearth roller 2 in a region having temperature exceeding temperature at which a thermal strain occurs to at least a plate-form substance A to be heated is narrowed to a value at which even when the plate-form substance A to be heated is placed directly on the hearth roller 2, so that no strain occurs thereto. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a roller hearth type continuous firing furnace for performing a heat treatment on a plate-like workpiece such as a glass substrate.

  For example, in order to form a film such as an electrode, a dielectric, and a phosphor on a glass substrate such as a plasma display panel substrate, a roller hearth type continuous firing furnace is used. In this roller hearth type continuous firing furnace, for example, a plate-like object to be heated such as a glass substrate is cooled in a tunnel-type furnace to a heating zone heated to a predetermined temperature, a slow cooling zone in which slow cooling is performed, and further to room temperature. The heat treatment is performed while being sequentially conveyed to the cooling zone. FIG. 3 is a schematic sectional view showing a conventional roller hearth type continuous firing furnace, which will be described.

  In this roller hearth type continuous firing furnace, as shown in FIG. 3, a plurality of hearth rollers 22 for transporting the plate-like heated object A below the tunnel-type furnace 21 through which the plate-like heated object A is passed. Is provided. The hearth roller 22 is generally attached with an outer diameter s of about 50 to 60 mm and a pitch interval d of about 200 mm. The hearth roller 22 is rotated by a motor (not shown), and the plate-like heated object A placed on the hearth roller 22 is conveyed by this rotation. At this time, in order to convey the plate-shaped heated object A in a stable state so as not to be distorted, the plate-shaped heated object A is not directly placed on the hearth roller 22, but is setter such as heat-resistant glass. The setter 23 is placed on the hearth roller 22 and is conveyed.

  However, in the conventional method in which the plate-like heated object A is placed on the setter 23 and conveyed, the plate-like heated object A and the setter 23 are simultaneously heated at the time of firing. There was a problem of increasing. At this time, since the setter 23 has substantially the same heat capacity as the plate-shaped object A and has a large volume ratio, the ratio of power consumed for heating the setter 23 increases, and power that is not necessary is consumed. It was. Further, the setter 23 is very expensive because it is polished to improve the flatness.

In a conventional roller hearth type continuous firing furnace, when the plate-shaped object A is placed directly on the hearth roller 22 and conveyed, the plate-shaped object to be heated is particularly heated in the heating zone or the slow cooling zone. In a region where the temperature is higher than the temperature at which distortion occurs, large distortion occurs in the plate-shaped object A, and the required accuracy cannot be satisfied.
The present invention has been proposed in view of the above circumstances, and even if a plate-shaped object to be heated is placed directly on a hearth roller without using a setter, the plate-shaped object is not distorted. An object of the present invention is to provide a roller hearth type continuous firing furnace capable of suppressing the generation.

  The present invention employs the following means in order to achieve the above object. That is, a plurality of hearth rollers for transporting the plate-shaped object to be heated are provided in a tunnel-type furnace that performs a series of heat treatments including heating and slow cooling according to a predetermined temperature condition. In the roller hearth type continuous firing furnace arranged at a predetermined pitch interval, at least the pitch interval in the region where the plate-like object to be heated is equal to or higher than the temperature at which thermal distortion occurs is generated without causing distortion in the plate-like object to be heated. The plate-like object to be heated is directly placed on a hearth roller so that it can be conveyed (Claim 1). Thus, by narrowing the pitch interval of the hearth rollers, the area where the plate-shaped heated object and the hearth roller are in contact, that is, the area supporting the plate-shaped heated object can be increased. As a result, it is possible to prevent the plate-like heated object from being bent by the gap between the hearth rollers, so even if the plate-like heated object is placed directly on the hearth roller without using a setter, it can be conveyed. And it can suppress that distortion generate | occur | produces in a plate-shaped to-be-heated material.

In the roller hearth type continuous firing furnace, it is desirable that at least the surface of the hearth roller at least in a region where the plate-shaped object to be heated is at or above a temperature causing thermal distortion is formed of fused silica. . In this case, since the surface of the hearth roller in contact with the plate-shaped object to be heated is fused silica, it is possible to make it difficult to damage the surface of the plate-shaped object to be heated.
Further, it is desirable that the surface roughness of the hearth roller at least in a region where the temperature of the plate-like heated object is higher than the temperature at which thermal distortion occurs is equal to or less than the surface roughness of the plate-like heated object. In this case, since the surface of the hearth roller in contact with the plate-shaped object to be heated is smoothly finished, it is possible to more effectively prevent the surface of the plate-shaped object to be heated from being scratched.

  As described above, in the roller hearth type continuous firing furnace according to the present invention, without causing distortion in the plate-like heated object, the plate-like heated object can be directly placed on the hearth roller and conveyed, Since the pitch interval of the hearth rollers in the region where the plate-shaped heated object is at least the temperature causing the thermal distortion is configured to be narrow, it is possible to prevent the plate-shaped heated object from being bent by the gap between the hearth rollers. it can. Accordingly, even if the plate-like heated object is directly placed on the hearth roller and transported without using a setter, it is possible to prevent the plate-like heated object from being distorted. In addition, since no setter is required for firing, it is possible to eliminate the cost of the setter. Further, since no setter is required for firing, it is only necessary to heat the plate-shaped object to be heated, and power consumption is reduced. Moreover, since a setter having a size larger than that of the plate-like object to be heated is not used, the furnace itself can be made small.

Further, when at least the surface of the hearth roller is formed of fused silica, the surface of the hearth roller in contact with the plate-like object to be heated is fused silica, so that it is difficult to damage the surface of the plate-like object to be heated. Can do.
In addition, when the surface roughness of the hearth roller is equal to or less than the surface roughness of the plate-like heated object, the surface of the hearth roller in contact with the plate-like heated object is smoothly finished. It is possible to more effectively prevent the surface of the surface from being scratched.

FIG. 1 is a schematic sectional view showing an embodiment of a roller hearth type continuous firing furnace according to the present invention, and FIG. 2 is a schematic view showing the entire configuration of this roller hearth type continuous firing furnace. The roller hearth type continuous firing furnace will be described below with reference to the drawings.
In this continuous firing furnace, as shown in FIG. 2, a heating zone B for heating the plate-like object A such as a glass substrate to a predetermined temperature, and a plate-like object A heated to the predetermined temperature are gradually cooled. A slow cooling zone C and a cooling zone D for further cooling the slowly heated plate-like object A to room temperature are provided. The plate-shaped object A is heat-treated while being sequentially moved in the tunnel-type furnace 1 to the heating zone B, the slow cooling zone C, and the cooling zone D.

  In the heating zone B and the slow cooling zone C of this roller hearth type continuous firing furnace, as shown in FIG. 1, the tunnel-type furnace 1 through which the plate-shaped object A is passed is composed of heat insulating materials on the upper surface, the lower surface and the side surfaces. It is comprised so that it may be covered with the heat insulation layer 5 to be formed. In the slow cooling zone C, the heat insulating layer 5 is configured such that the thickness of the heat insulating layer 5 decreases as the thickness of the plate-shaped object A increases. In the furnace 1, there are a bottom heater 3 for heating the inside of the furnace 1 below, a plurality of hearth rollers 2 for transporting the plate-like object A above the bottom heater 3, and A top heater 4 for heating the inside 1 is provided.

  The hearth roller 2 is attached with a narrow pitch interval d so that a gap generated between the adjacent hearth rollers 2 is reduced. Here, for example, the outer diameter s is 30 mm, and the pitch interval d is 50 mm. Thus, by narrowing the pitch interval d between the hearth rollers 2, the area where the plate-like heated object A and the hearth roller 2 are in contact, that is, the area where the plate-like heated object A is supported increases. Thereby, when the plate-like heated object A is directly placed on the hearth roller 2 and conveyed, it is possible to prevent the plate-like heated object A from being distorted. If the pitch interval d of the hearth rollers 2 is narrowed, the number of the hearth rollers 2 that the plate-like heated object A comes into contact with increases, so that the load applied to one hearth roller 2 decreases. Can be reduced. Therefore, the outer diameter s and the pitch interval d of the hearth roller 2 that can suppress the generation of distortion as much as possible are determined according to the characteristics (strength, size, etc.) of the plate-like heated object A.

  The hearth roller 2 is made of fused silica, and the surface is finished with a surface roughness (centerline average roughness) of 5 μm or less. As described above, since the hearth roller 2 in contact with the plate-like object to be heated A is made of fused silica and the surface is smoothly finished, it is possible to effectively prevent the surface of the plate-like object to be heated from being scratched. Can do. Further, the hearth roller 2 is rotated by a motor (not shown), and the plate-like heated object A placed directly on the hearth roller 2 is conveyed by this rotation.

In addition, in this Embodiment, although the above structures about attachment of the hearth roller 2 are employ | adopted for the heating zone B and the slow cooling zone C, it is not restricted to this. For example, the hearth rollers 2 in all the zones in the furnace 1 can be configured in the same manner as described above, but at least the temperature at which the plate-shaped object to be heated in the heating zone B and the slow cooling zone C is subjected to thermal distortion. It suffices if the region to be configured is similar to the above. Here, the temperature at which the plate-like object to be heated is subjected to thermal strain is, in the case of a glass substrate, a theoretical guideline that is equal to or higher than the strain point, but is not limited to this. There is a case where a margin is taken to a temperature lower by 100 to 200 ° C., for example, up to around 400 ° C.
In the present embodiment, the hearth roller 2 is made of fused silica. However, at least the surface of the hearth roller 2 is made of fused silica, such as a metal tube whose surface is coated with fused silica. That's fine.

1 is a schematic cross-sectional view showing an embodiment of a roller hearth type continuous firing furnace according to the present invention. It is the schematic which shows the whole structure of one Embodiment of the roller hearth type | formula continuous baking furnace which concerns on this invention. It is a schematic sectional drawing which shows the conventional roller hearth type | mold continuous baking furnace.

Explanation of symbols

A Plate-like heated object B Heating zone 1 Furnace 2 Hearth roller s Outer diameter d Pitch interval

Claims (3)

A plurality of hearth rollers for transporting the plate-shaped object to be heated are provided at predetermined pitch intervals in a tunnel-type furnace that performs a series of heat treatments including heating and slow cooling according to a predetermined temperature condition. In the arranged roller hearth type continuous firing furnace,
Place the plate-like heated object directly on the hearth roller without causing distortion in the plate-like heated object at least at the pitch interval where the plate-like heated object is at or above the temperature at which thermal distortion occurs. A roller hearth-type continuous firing furnace characterized in that the interval can be conveyed.   2. The roller hearth type continuous firing furnace according to claim 1, wherein at least a surface of the hearth roller in a region where at least the temperature of the plate-like object to be heated becomes higher than a temperature at which thermal distortion occurs is formed of fused silica.   3. The roller hearth according to claim 1, wherein a surface roughness of the hearth roller in a region where at least the temperature of the plate-like heated object is higher than a temperature causing thermal distortion is equal to or less than a surface roughness of the plate-like heated object. Type continuous firing furnace.

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